Perhaps this discussion needs some hard numbers. I ran some data this morning on every fandom book I could find, looking at the gender of the main character and gender of the author.
I counted 89 books. This list excluded: Graphic novels, anthologies (collections by the same author were included), books not written in/for the fandom (thus no Ratha, no Redwall, etc), books that had both male and female main characters, books where it was not clear (Chains of Silver, Chains of Gold has a trans-male, so I wasn’t sure what to do with that; a few books based on descriptions did not make it the gender of the main character, either), and a lot of M. C. A. Hogarth’s stuff because I couldn’t tell if it was a book or a short story, what collection it appeared in, and didn’t feel like going through every single one - from her, I used Claws & Starships, Blades & Bitter Apples, and Spots the Space Marine. It’s also possible I was wrong about one or two books. I can provide the title, protagonist and author list if anyone asks.
Main characters: 63 books had male protagonists (70.8%), 26 books had female protagonists (29.2%).
Author Gender: 10 books were written by females (11.2%), 79 were written by males (88.8%)
Of the 79 books written by male authors, 18 (20.2%) had female main characters. Of the 10 written by women, 2 (20%) had male main characters. Of the 26 books with female main characters, 18 (68.2%) were written by men, compared to the 8 (30.7%) by women.
Additionally, I measured whether the book was focused as gay erotica or not, under the assumption that a gay erotica would not have a female protagonist because A) that’s counter-productive and B) not the target audience anyways. Gay erotica: Yes: 32 (36%), No: 57 (64%); therefore of the 79 written by men, 40.5% were gay erotica. One author wrote gay erotica There were one or two books which I was not sure whether were gayerotica or not, so were not included.
If we removed the 40% of gay erotica from the list, then we only have 57 total books, 47 books written by male authors. Of those 57 books, female main characters appear in 26 (45.5%), to males 31 (54.5%).
Based on these numbers, it looks like male authors are writing most of the female main characters, and if you exclude gay erotica, female main characters appear almost half the time.